Method of installing control lines in a wellbore

ABSTRACT

A method and apparatus for perforating a casing in a wellbore wherein the casing has control means attached thereto, which method and apparatus includes inserting a detectable source with the control means extending a selected length of the control means; inserting a sensing means in the casing for sensing the detectable source; sensing the location of the detectable source at selected levels in the casing; recording the direction of the detectable source at the selected levels in the casing; inserting perforating means in the casing, the perforating means for perforating the casing, the perforating means having orienting means for selectively positioning the perforating means relative to the recorded direction of the detectable source at the selected levels in the casing; and perforating the casing at a selected orientation relative to the sensed detectable source at the selected levels in the casing.

BACKGROUND OF THE INVENTION

[0001] 1. Field of Invention

[0002] This invention relates to well drilling and completion devicesand processes. More specifically, the invention is concerned withproviding devices and methods that improve the ability to azimuthallyorient perforating devices away from downhole cables within aperforating zone. And more particularly, to such an apparatus andprocess wherein a detectable source is employed to identify the locationof the control lines.

[0003] 2. Background of the Invention

[0004] Conventional wells and well completions typically provide littleor no downhole instrumentation and/or fluid control capability. Someconventional well completion procedures are relatively simple,essentially running production or injection tubing into the well alongwith perforating, gravel packing, and/or logging steps as needed.Pressure and flow control in conventional oil, gas or otherfluid-producing wells typically use valves and instruments located at ornear the surface in a Christmas tree arrangement. Formation fluids aretypically produced until a downhole problem occurs, e.g., reservoirpressure declines or the water-cut increases or something else happensdownhole that significantly reduces production or prevents the well fromfurther commercial operation.

[0005] To evaluate the cause of production or injection problems in aconventional well, the well is typically taken off-line and one or morelogging tools supported by a wireline are run through the tubing withinthe well. The logging tools may be used to check downhole fluidpressures, fluid types, zonal flowrates or other parameters at one ormore depths to try to determine the cause of the production or injectiondecline and the corrective action needed. Once the problem is determinedand/or new production or injection zones identified, the wireline toolsare typically removed and a second re-entry into the off-line well isaccomplished to correct the problem, e.g., using a workover rig. Forexample, a second re-entry might lower a perforating tool toreperforate/re-complete the well at a new producing level. Theseconventional well completions, re-entries, and recompletions may consumeunacceptable lost production time and costs, especially when applied todeepwater, multi-producing zone, high temperature, and/or high-pressurereservoirs and wells. In contrast to conventional wells and wellsystems, the term “intelligent” and “smart” wells and well systems mayrefer to wells having downhole process control, instrumentation, and/orrelated components. Other terms used for intelligent or smart wellsystems include SCRAMS (Surface Controlled Analysis and ManagementSystem), IRIS (Intelligent Remote Implementation System), and RMC(Reservoir Monitoring & Control). But no matter what these well systemsare called, they enable real-time downhole operation, surveillance, datainterpretation, intervention, and/or process control in a continuousfeedback loop. The smart wells allow problems to be detected andpossibly minimized or corrected without taking the well off-line. Smartwell systems can therefore operate for long periods without the need toshut down and introduce instrumentation or additional wireline tools.However, the introduction of perforating tools is still typicallyrequired during the less frequent workover processes.

[0006] A smart well system typically uses downhole tubing, cables orother means for transmitting power, real-time data or control signals toor from surface equipment and downhole devices such as transducers andcontrol valves. Power and signals typically use transmission means suchas electric and/or fiber optic cables, but other transmission devicescan include fluid tubing. Other well applications may also have cablesor other transmission means present during operations that may includeperforating. Other well processes and applications that may requiredownhole transmission means include wells having a submersible electricpump, measurement while drilling (MWD) methods, and the use of downholedirectional & inclination indicators, hydraulic actuators, and powersupplies, e.g., for data transmission using mud pulse telemetry.Perforating or re-perforating a well having a downhole cable or othertransmission device must avoid damaging the transmission device duringthe perforating process, typically requiring a step of azimuthallyorienting a directional-perforating device. The orienting step directsthe perforating action away from nearby cables or other devices in thewell. Orientating methods may include magnetic oriented techniques(MOT), obtaining positional data from downhole probes, usinggravity-actuated orienting devices for non-vertical boreholes, limitingoperations to within guided downhole paths, obtaining orienting datafrom gyroscopes, and using mechanical indicators or orientation subs.

[0007] However, the orienting step can add significant cost and/orpresent feasibility problems, especially when high temperature,corrosive fluids, high pressures, multiple completion zones, or otherdifficult downhole conditions are encountered. The added costs andproblems can also be compounded by the added time to accomplish theorienting step for deep offshore wells. For example, application ofcurrent MOT techniques may be limited by high downhole temperatures andsince typical well depths have been increasing, increasing downholetemperature problems for MOT processes may be encountered.

[0008] 3. Description of Related Art

[0009] After a wellbore has penetrated a formation and a casing has beencemented in place, the formation must be communicated with the wellheadso that valuable hydrocarbons or other effluents can be extracted fromthe wellhead. The standard method of communicating the formation withthe wellhead is to perforate the casing so that the hydrocarbons orother effluents may penetrate the casing. The methods of perforating thecasing are well known to those of ordinary skill in the art of oil, gasand geothermal exploration and extraction. U.S. Pat. Nos. 3,706,344 and3,871,448 to Roy R. Vann teach a permanent completion technique whichcan advantageously be employed in completing a wellbore. Reference ismade to these prior patents, to U.S. Pat. Nos. 3,931,855; 3,812,911; and4,040,485; and to the art cited therein for further background of thepresent invention.

[0010] The well completion method and apparatus of the present inventionis applicable to any well that is completed with casing cemented acrossthe producing interval, which implies perforating is required, andparticularly applicable to deep, high-temperature, high-pressure wells.For example, such a well might be over 10,000 feet deep, have abottomhole temperature of about 300° F., and bottomhole pressure of over5,000 psi. Because of this environment, it is essential for safetyreasons that control be maintained over the well at all times. Suchcontrol is maintained by using a hydrostatic head of well fluids such asmud to insure that the bottomhole pressure exceeds the formationpressure and later setting a packer in the eased wellbore. Typically theproduction casing consists of a number of individual lengths of casingcoupled together by means of collars that are in a spaced relationshipalong the length of the production casing. It is known in the trade toinclude identification pip tags at the collars so that they may beidentified by detection means, the primary use of such pip tags is fordepth location only. The pip tags enable the operator to tie into anexact well depth for any vertical correlation work being done.

[0011] It would be desirable to be able to run the control lines intothe wellbore across the interval to be perforated, attached to theoutside of the production casing. The sensing of wellbore temperature ismeasured from that exact location at a selected depth, which will not beexactly what the temperature is on the inside of the casing, but will besimilar given enough thee for equalization. To sense pressure, thepressure sensor is communicated to the internal casing pressure by meansof a port between the interior of the casing and the sensor itself.After the production casing is inserted in the wellbore, the location ofthe collars are known, however the collars cannot prevent the skewing ofthe control lines circumferentially around the outside of the productioncasing due to the high pressures and other conditions encountered whileinserting the casing. Thus, the precise location of the control lines onthe perimeter of the casing at any given depth is not known, so that theopportunity, or probability, for damaging the control lines duringprocess of perforating the production casing is high, which would renderthem either partially or wholly useless. Therefore there is a need for amethod and an apparatus for locating the precise location of the controllines at a selected depth so that the perforation means may be orientedin a selected direction to avoid damaging the control lines. Method andapparatus for accomplishing this purpose is the subject of the presentinvention.

SUMMARY OF THE INVENTION

[0012] In one embodiment, the invention adds a position signaling or adetectable signature element to a cable or other equipment to beprotected and a signal or signature position detector that, at least inpart, controls the orientation of a directed perforating device. Thedetection of the position signal or signature allows the perforatingdevice to be oriented in a desired azimuthal position that avoidsdamaging the cable. Signal emitting sources can include a radioactivematerial added to an encapsulating composition of a downhole cable or anirradiated cobalt alloy wire along with electric wires in the cable.Various types of signal detectors can be used, e.g., a Geiger, Mueller,or scintillation counter, combined with a moveable apertured shield oranother directional device, e.g., a Rotascan and/or Tracerscan modelmanufactured by Halliburton and available-in Houston, Tex. or a POT-Cmanufactured by Schlumberger and available in Houston, Tex. The positionsignal detector assembly is preferably connected to a scallop, stripgun, or other conventional directed perforating tool (e.g., a Model OPperforating tool supplied by Halliburton) in such a way thatperforations are directed away from the detected cable or cableassembly. Connecting the directed perforating tool and the signaldetector allows a reliable perforation and reperforation of the wellwithout. re-entry and without damage to the cable or other downholeequipment not intended to be perforated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a fragmentary, partly diagrammatic, partlycross-sectional elevation of a wellbore containing apparatus of thepresent invention.

[0014]FIG. 2 is a schematic representation of the apparatus of thepresent invention.

[0015]FIG. 3 is a cross-sectional view of the apparatus of FIG. 2through a first element of orientation means of the apparatus of thepresent invention.

[0016]FIG. 4 is a cross-sectional view of the apparatus of FIG. 2through the detection means of the apparatus of the present invention.

[0017]FIG. 5 is a plan view of the apparatus of FIG. 2 inside thewellbore casing.

[0018]FIG. 6 is a schematic view of one embodiment of the detectablesource of the invention attached to the control means.

[0019]FIG. 7 is a schematic view of a second embodiment of thedetectable source of the invention attached to the control means.

DETAILED DESCRIPTION OF THE INVENTION

[0020]FIG. 1 discloses a partial sectional view of a cement-sleevedwellbore 20, at a particular depth in a formation 10. Wellbore 20 is acylindrical, cement casing extending from the surface to a selecteddepth in formation 10 where valuable effluent may reside. Wellbore 20may be capped at the surface (not shown) to maintain pressure in thewellbore. Shown within wellbore 20 is production casing 30 that iscemented in formation 10 by wellbore 20, and containing apparatus of thepresent invention consisting of a tool 40 which has a plurality ofcomponents for communicating the wellbore with the formation 10. Tool 40consists of a rotational means 50, a detection housing 60, a means ofperforation 70, and means 45 for lowering tool 40 to a desired depth inproduction casing 30. FIG. 1 discloses that wellbore 20 has beencommunicated with formation 10 by means of a plurality perforation holes140 through production casing 30, wellbore 20 and into formation 10 toenable effluents in formation 10 to flow into production casing 30.

[0021] Production casing 30 is typically about 4.5 to 9 inches insidediameter d and constructed of steel. Production casing 30 is generallyinserted inside a larger steel tube that is run from the surface to ashallower depth. Consecutively smaller diameters of casing are run todeeper depths, each in side the previous. Casing sizes can be of about20 inches inside diameter at the surface, and narrowing to about 9inches inside diameter at the bottom of the wellbore. Production casing30 may be 5,000 to 10,000 feet in length, and is of sufficient strengthto withstand 5,000 pounds per square inch pressure at such depths.Attached to the outside of production casing 30 is control means 80extending a selected distance in the wellbore. Control means 80 mayconsist of an electrical line, a single tube containing an electricallead for operating a device, a capillary tube for determining thepressure of the wellbore at a selected depth, and/or a plurality ofelectrical lines or leads, capillary tubing, fiber optic cables, orother control means for measuring various parameters in the wellbore, orfor operating a variety of devices in the wellbore. Control means 80 isattached to production casing 30 by a plurality of casing collarprotector clamps that are placed over each casing collar 35 (FIGS. 6 &7) which may be located at selected and known intervals along productioncasing 30. The collars are located at the end of each joint of casing,and are merely the apparatus to couple the joints of casing together.However, they typically are a larger outside diameter than casingitself. In FIG. 1, control means 80 includes a detectable source 90,which may be detected by detection means 68 at any selected depth alongcasing 30. Means 45 for lowering tool 40 in wellbore 20 is typically abull nose, or sinker bars, or a combination thereof, that pull tool 40into production casing 30 by gravity. The number of bull noses and/orsinker bars are selected based on the depth of production casing 30 andthe wellbore pressure. These factors are well known to one of ordinaryskill in the art and are not limitations to the present invention.Lowering means 45 is typically added to tool 40 by a threaded meansprojecting from the last device in the tool string in the well, and inthis embodiment, from perforation means 70. Emanating horizontally fromwellbore 20 are a plurality of perforations 140 which penetrate casing30, wellbore 20 into formation 10.

[0022]FIG. 2 is an elevation view of tool 40 apart from the wellbore.Tool 40 is typically suspended in the wellbore by cable 95, and consistsof three components, the rotational means 50, the detection housing 60,the perforation means 70, and means 45 for lowering tool 40 in theproduction casing 30. Rotational means 50 may be controlled by anoperator at the surface at some point adjacent the wellbore by operationmeans 100 which communicates with tool 40 by means of communicationcable 95 that may include an electrical source to operate tool 40.Alternatively, operation means 100 may be a programmed means, such as acomputer. In an alternate embodiment, operation means 100 may include atransmitter or transceiver that may communicate with a receiver ortransceiver in rotational means 50 to control operation of tool 40 andwherein tool 40 includes a source of electricity, such as a battery.

[0023] As shown in FIG. 2, intermediate in detection housing 60 isdetection slot 65, which exposes detection means 68 (FIG. 4) to theinterior of production casing 30. In this preferred embodiment,detection housing 60 is fabricated of a high densityshielding/insulating material, such as lead or tungsten, therebyshielding detection means 68 from detecting the detectable source 90from any direction other than through detection slot 65. The materialselected for housing 60 is based on the type of detectable source 90,for example, if the detectable source 90 is a magnetic field devicethen, housing 60 would be not require a detection slot 65.

[0024] Referring to FIGS. 3, 4 and 5, FIG. 3 is a cross-sectional viewof rotational means 50. In this preferred embodiment rotational means 50is an electrical driven motor 55 in a cylindrical housing, that causesshaft 52 to rotate about its longitudinal axis, and in parallel with thelongitudinal axis of production casing 30. In fixed relationship withrotational means 50 is cylindrical detection housing 60, which isthreadedly attached to Shaft 52 of rotational means 50 such thatdetection housing 60 is fixed relative to rotational means 50, and thussynchronously rotates about the longitudinal axis of Shaft 52. Extendingperpendicularly from the bottom of detection housing 60, co-axially withshaft 52, is detection housing shaft 62, which is sized and threadedlyconfigured identical to shaft 52 for fixedly receiving perforation means70. Thus, one can appreciate that detection housing 60 could be removedfrom device 40 and perforation means 70 attached directly to shaft 52.Perforation means 70 will rotate synchronously about the longitudinalaxis of shaft 52 in fixed relationship to both shaft 52 and detectionhousing 60. Thus when detection means 68 is rotated about thelongitudinal axis of shaft 52 within production casing 30 by rotationalmeans 50, and when detection slot 65 becomes proximate to detectablesource 90, the location of detectable source 90 may be noted relative tothe then current position of shaft 52. Therefore, the exact location ofcontrol means 80 is then known at that selected depth in the wellbore.To ensure that the control means 80 is at the precise detected locationrelative to shaft 52, it may be desirable to rotate detection means 65past detectable source 90 several times. Geometrically, detectionhousing 60 and perforation means 70 can be viewed as canisters, whereinthe top surface of the canister includes a threaded receptacle (notshown) for receiving shafts 52 and 62, respectively and the bottom ofthe receptacle includes threaded means 62 and 72 for connecting toperforation means 70 and lowering means 45, respectively. In thepreferred embodiment, detection housing 60 abuts firmly against thebottom of rotational means 50, and perforating means 70 abuts firmlyagainst the bottom of detection housing 60. It may be desired toposition gaskets at each abutment so that effluent from the wellbore issealed from obstructing or interfering with the rotational aspects ofdevice 40. Concomitantly, it may be desirable to fill detection slot 65with a high-pressure, high-temperature glass (either limited ornon-gamma ray absorbent material), or equivalent material, that wouldseal detection means 68 from the effluent without deteriorating theperformance of the sensor. It should also be appreciated that there areother means by which detection housing 60 and perforating means 70 maybe attached to rotation means 50, as would be known by one of ordinaryskill in the art. For example, detection housing 60 and perforatingmeans 70 could be mounted on a common shaft, or mounted is a singlehousing.

[0025]FIG. 5 depicts a plan, cross-section of perforating means 70.Perforating means 70 is shown to be resting adjacent production casing30, which one of ordinary skill in the art would know is typical, sinceproduction casing 30 cannot be run perfectly vertical into formation 10.As noted above, perforating means 70 is threadedly attached to detectionhousing 60 such that perforating means 70 is also fixed relative torotational means 50, thus also fixed in relationship with the axis ofshaft 52 so that the radial alignment of perforating means 70 relativeto shaft 52 is also known, and therefore the location of control means80 is known when detected by detection means 68. The location andposition of perforating means 70 may be pre-oriented such that whendetection means 68 identifies the location of detectable source 90adjacent or within control means 80 at that selected depth (so as toavoid the casing collars) and within the area of valuable effluent, thenperforation of production casing 70 and wellbore 20 is simplyaccomplished by firing perforation means 70 in a selected direction awayfrom control means 80. Alternatively, by orienting perforating means 70in the same orientation relative to the position of detection means 68,perforation of production casing 30 and wellbore 20 is accomplished byrotating shaft 52 a selected number of degrees away from control means80, and firing perforation means 70.

[0026] Since it is possible to selectively fire perforation means 70 aplurality of times, it is then possible, after the initial perforatingthe casing, to relocate tool 40 to a different selected depth, and toagain rotate detection means 68 past detectable source 90, (which, asnoted above, may have moved circumferentially with control means 80about production casing 30 an unknown distance) to again locatedetectable source 90 at that newly selected depth, and then againperforate production casing 30 and wellbore 20 ind into formation 10.Referring again to FIG. 2, perforation means 70 is shown to include aplurality of perforation guns 75 projecting outwardly from thelongitudinal axis of shaft 52. This process of perforation may becontinued until the complete production casing 30 and wellbore 20 havebeen perforated through the selected area of the valuable effluent.Since detectable source 90 is permanently installed as part of controlmeans 80, if perforation means 70 fails for any reason, tool 40 may beremoved from production casing 30, repaired, and reinserted inproduction casing 30 for completion of the work. Alternatively, if it issubsequently desired to perforate production casing 30 and wellbore 20at a different selected depth, tool 40 may again be inserted inproduction casing 30, and the location of control means 80 may still belocated, even though it may have circumferentially shifted aboutproduction casing 30 from forces within wellbore.

[0027] In another embodiment of the method of the invention, tool 40 maybe assembled without perforation means 70, and tool 40 may be lowered inproduction casing 30 for the selected length of the casing whereperforations are desired. By continuously monitoring the location ofdetectable source 90 at selected intervals, the exact location ofcontrol means 80 throughout the selected length of production casing 30may be communicated to operation means 100, thereby enabling athree-dimensional mapping, or profiling, of control means 80 relative toproduction casing 30. In this embodiment, the azimuth (a horizontaldirection expressed as the angular distance between the direction of afixed point, such as the position of shaft 52, or the direction towardmagnet north pole) denoting the direction of detectable source 90 ateach selected depth, would be communicated to operation means 100, toenable the three-dimensional mapping of production casing 30. Once theselected length of production casing 30 has been profiled, tool 40 maybe removed from production casing 30, the detection means replaced withperforation means 70, and tool 40 run back into production casing 30 forthe perforation step. By having previously profiled control means 80relative to production casing 30, perforation means 70 may be optimized.Directional perforating can be performed by utilizing a directionallyweighted perforated tool and pre-setting the azimuthal direction for aspecific depth. For example, it may be possible to string a largernumber of perforating guns in perforation means 70 to enable a moreefficient and time savings perforation of the formation, as would beobvious to one of ordinary skill in the art.

[0028]FIGS. 6 and 7 are schematic diagrams of portions of productioncasing 30 showing detectable source 90 attached thereto, but withoutshowing control means 80. In FIG. 6, detectable source 90 can be amagnetic or irradiated wire extending the selected length of productioncasing 30, and held in place by a plurality of collars protector clamps35. Alternatively, detectable source 90 could be a capillary tubecontaining the magnetic or irradiated wire, or a detectable radioactivefluid. FIG. 7 shows detectable source is a magnetic or irradiated strip,adjacent control means 80, and extending a selected distance above andbelow each collar 35. In either case, the detectable source 90 andcontrol means 80 are shown to be vertically aligned along the length ofproduction casing 30, however, as noted above, and as known to one ofordinary skill in the art, upon insertion of casing 30 into formation10, the process of insertion, and the conditions of the formation, willcause control means 80 and detectable source 90 to be skewedcircumferentially about production casing 30.

[0029] Detectable source 90 may be of various compositions. For example,control means 80 may include a capillary tube extending the length ofcontrol means 80, closed at both ends, and containing a detectable gas,such as Krypton, or an irradiated source, such as an irradiated wire.Equivalently, an irradiated wire may be included as part of the controlmeans. Detection means 68 could then be a Geiger Mueller tube, or anequivalent radiation/gamma-ray detector or scintillation counter,combined with a moveable apertured shield or another directional device,e.g., a Rotascan and/or Tracerscan model manufactured by Halliburton andavailable-in Houston, Tex. or a POT-C manufactured by Schlumberger andavailable in Houston, Tex. Alternatively, detection means 68 could be adirectional variation magnetic field sensor. The present invention isnot limited by the detectable source or the detection means. It is onlynecessary that the detectable source extend a substantial length ofcontrol means 80 in the selected area of the wellbore to be perforated.The detectable source may be discontinuous, as long as it enables theoperator of the tool to identify the location of the control tubing at aselected depth and, at the same time, avoid the casing collars.Detectable source 90 could be a wire having a major component beingcobalt. Irradiated wire may be produced by spooling the wire in-linethrough the neutron field emitted by a nuclear reactor. In addition, theDetectable source 90 may be installed inside control means 80 during themanufacturing process of control means 80, or attached to control means80 during the production casing installation process.

[0030] Perforation means 70 is commonly a perforating gun, or a stringof guns. The term “gun” implies a length of perforating charges that cancover a selected number of feet to be perforated. Guns usually havecharges ranging from 2 to 12 shots per foot with these charges spacedcircumferential at various and known angles from charge to charge. Astring of guns implies connecting multiple gull segments of charges. Thecharges can be spaced to leave a long length of non-perforated intervalbetween segments where perforations are required.

[0031] Accordingly, the scope of the invention should not be determinedby the specific embodiments illustrated herein, but rather in light ofthe full scope of the claims appended hereto.

We claim:
 1. A method for perforating a casing in a wellbore, the casinghaving control means attached thereto, the method comprising: (a)inserting a detectable source with the control means, the detectablesource extending a selected length of the control means; (b) inserting asensing means in the casing, the sensing means for sensing thedetectable source; (c) inserting perforating means in the casing, theperforating means for perforating the casing, the perforating meanshaving orienting means for selectively positioning the perforating meansrelative to the direction of the detectable source; (d) sensing thelocation of the detectable source; and (e) perforating the casing at aselected orientation relative to the sensed detectable source.
 2. Themethod of claim 1 wherein the detectable source is a source ofradiation.
 3. The method of claim 2 wherein the source of radiation isan irradiated wire.
 4. The method of claim 1 wherein the step ofinserting the detectable source includes inserting at least onecapillary tube extending a selected length of the control means.
 5. Themethod of claim 4 wherein the step of inserting at least one capillarytube includes the step of inserting the detectable source in thecapillary tube.
 6. The method of claims 5 wherein the detectable sourceis a fluid.
 7. The method of claim 2 wherein the sensing means forsensing the source of radiation is a gamma ray detector.
 8. The methodof claim 1 wherein the detectable source is a magnetic wire.
 9. Themethod of claim 8 wherein the sensing means is a directional variationmagnetic field sensor.
 10. The method of claim 1 wherein the step ofperforating the casing at a selected orientation relative to thedetectable source includes orienting the perforating means away from thecontrol means.
 11. The method of claim 1 wherein the orienting means isa motor for providing rotational bias to the sensing means and theperforating means.
 12. The method of claim 1 wherein the perforatingmeans is a perforating gun.
 13. A method for perforating a casing in awellbore, the casing having control means attached thereto, the methodcomprising: (a) inserting, in fixed relationship with the control means,at least one capillary tube, the capillary tube extending a selectedlength of the control means; (b) inserting in the capillary tube adetectable source, the detectable source extending a selected length ofthe capillary tube; (c) inserting a sensing means, the sensing means forsensing the detectable source; (d) inserting a perforating gun in thecasing, the perforating gun for perforating the casing and the wellbore,the perforating gun having orienting means for selectively positioningthe perforating gun relative to the direction of the detectable source;(e) detecting the location of the detectable source; and (t) perforatingthe casing at a selected orientation away from the control means. 14.The method of claim 13 wherein the source of radiation is an irradiatedwire.
 15. The method of claims 16 wherein the radiation source is afluid.
 16. The method of claim 14 wherein the sensing means for sensingthe source of radiation is a gamma ray detector.
 17. The method of claim13 wherein the detectable source is a magnetic wire.
 18. The method ofclaim 17 wherein the sensing means is a directional variation magneticfield sensor.
 19. The method of claim 13 wherein the step of perforatingthe casing at a selected orientation relative to the detectable sourceincludes orienting the perforating gun.
 20. The method of claim 19wherein the orienting means is a motor for providing rotational bias tothe sensing means and the perforating gun.
 21. A method for perforatinga casing in a wellbore, the casing having control means attachedthereto, the method comprising: (a) inserting a detectable source withthe control means, the detectable source extending a selected length ofthe control means; (b) inserting a sensing means in the casing, thesensing means for sensing the detectable source; (c) sensing thelocation of the detectable source at selected levels in the casing; (d)recording the direction of the detectable source at the selected levelsin the casing; (e) inserting perforating means in the casing, theperforating means for perforating the casing, the perforating meanshaving orienting means for selectively positioning the perforating meansrelative to the recorded direction of the detectable source at theselected levels in the casing; and (f) perforating the casing at aselected orientation relative to the sensed detectable source at theselected levels in the casing.
 22. The method of claim 21 wherein thestep of recording the direction of the detectable source at the selectedlevels in the casing includes the step of removing the detection meansprior to inserting the perforating means in the casing.
 23. The methodof claim 21 wherein the detectable source is a source of radiation. 24.The method of claim 23 wherein the source of radiation is an irradiatedwire.
 25. The method of claim 21 wherein the step of inserting thedetectable source includes inserting at least one capillary tubeextending a selected length of the control means.
 26. The method ofclaim 25 wherein the step of inserting at least one capillary tubeincludes the step of inserting the detectable source in the capillarytube.
 27. The method of claims 26 wherein the detectable source is afluid.
 28. The method of claim 23 wherein the sensing means for sensingthe source of radiation is a gamma ray detector.
 29. The method of claim21 wherein the detectable source is a magnetic wire.
 30. The method ofclaim 29 wherein the sensing means is a directional variation magneticfield sensor.
 31. The method of claim 21 wherein the step of perforatingthe casing at a selected orientation relative to the detectable sourceincludes orienting the perforating means away from the control means.32. The method of claim 21 wherein the orienting means is a motor forproviding rotational bias to the sensing means and the perforatingmeans.
 33. Apparatus for perforating a casing in a wellbore, the casinghaving control means attached thereto, the apparatus comprising: (a) adetectable source, the detectable source for inserting in a fixedrelationship with the control means, the detectable source foridentifying the location of the control means, the detectable sourcesized to extend a selected length in the casing; (b) orientation means,the orientation means for selectively orienting sensing means andperforating means relative to the detectable source; (c) sensing meansfor sensing the detectable source, the sensing means for insertion inthe casing, the sensing means in fixed relationship to the orientationmeans; and (d) perforating means for perforating the casing, theperforating means 11 fixed relationship with the orientation means. 34.The apparatus of claim 33 wherein the detectable source is a source ofradiation.
 35. The apparatus of claim 34 wherein the source of radiationis an irradiated wire.
 36. The apparatus of claim 33 additionallyincluding at least one capillary tube, the at least one capillary tubesized to extend a selected length of the control means, the capillarytube for receiving the detectable source.
 37. The apparatus of claim 33wherein the detectable source is a fluid.
 38. The apparatus of claim 34wherein the sensing means is a gamma ray detector.
 39. The apparatus ofclaim 33 wherein the detectable source is a magnetic wire.
 40. Theapparatus of claim 39 wherein the sensing means is a directionalvariation magnetic field sensor.
 41. The apparatus of claim 33 whereinthe orienting means is a motor for providing rotational bias to thesensing means and the pert-orating means.
 42. The apparatus of claim 33wherein the perforating means is a perforating gun.
 43. Apparatus forperforating a casing in a wellbore, the casing having control meansattached thereto, the process comprising: (a) at least one capillarytube in fixed relationship to the control means, the at least onecapillary tube sized to extend a selected length of the control means,the capillary tube for receiving a detectable source (b) the detectablesource for identifying the location of the bundle, the detectable sourcesized to extend a selected length in the capillary tube; (c) a motor forproviding rotational bias to sensing means and perforating means, themotor for selectively orienting a perforating gun relative to thedetectable source; (d) sensing means for sensing the detectable source,the sensing means for insertion in the casing, the sensing meanscommunicating with and in fixed relationship to the motor; and (e) theperforating guns for perforating the casing, the perforating gun infixed relationship to the motor.
 44. The apparatus of claim 43 whereinthe detectable source is a source of radiation.
 45. The apparatus ofclaim 44 wherein the source of radiation is an irradiated wire.
 46. Theapparatus of claim 43 wherein the detectable source is a fluid.
 47. Theapparatus of claim 44 wherein the sensing means for sensing the sourceof radiation is a gamma ray detector.
 48. The apparatus of claim 43wherein the detectable source is a magnetic wire.
 49. The apparatus ofclaim 48 wherein the sensing means is a directional variation magneticfield sensor.